Publikationsserver der RWTH Aachen University
Asymmetric synthesis of medium-sized carbocycles spirocycles and oxabicycles via ring closing metathesis sufoximine substituted trienes and dihydropyran derivates
Abstract
dc:descriptionThe synthesis of substituted chiral medium-sized carbocycles is an important goal of organic synthesis. Ring-closing metathesis of acyclic dienes is a very effective method for the synthesis of medium-sized carbocycles. In this project, sulfoximine-substituted trienes were proven to be excellent parent compounds for the selective synthesis of Z-configured medium sized carbocycles. The formation of sulfoximine-substituted trienes, key intermediates of the described synthesis, was accomplished via a-functionalization of the corresponding sulfoximine-substituted homoallylic alcohols, whereby several protocols were developed. With the spectrum of sulfoximine-substituted trienes at hand, we investigated their RCM. Thus, the products of a-functionalization described above were treated with Grubbs second generation catalyst to give the desired carbocycles in very good yields. Interestingly, all carbocycles were obtained exclusively as Z-configured isomers, only in the case of the 11-membered carbocycle formation of a small amount of E-configured isomer was observed. Finally, sulfoximine moiety was removed from carbocycles. In the case of seven-membered carbocycle methyl group was introduced via cross-coupling reaction with methyl cuprate. The nine membered carbocycle was treated with aluminium amalgam to give corresponding carbocycle without sulfoximine-moiety. Sulfoximine-mediated strategy was also applied to a synthesis of spirocyclic and oxabicyclic compounds. The key compounds of our synthesis were the sulfoximine-substituted pyrans, which served as parent compounds for spiroketals, spiroethers and oxabicycles. Spiroketals and spiroethers were synthesized via introduction of a suitable substituent in the a-position of pyrans followed by RCM. Chloride-substituted spiroethers were synthesized via the Prins reaction of the corresponding sulfoximine –substituted pyrans bearing 1-pentenyl substituent. The synthesis of pyrans was accomplished via deprotection-cyclization of the corresponding a-sulfoximido ketones.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2008
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Lejkowski, Michal
- Contributors dc:contributor
-
- Gais, Hans-Joachim
Subjects
dc:subject × 12Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- eng